(1) Field of the Invention
The present invention relates to a circuit for protecting at least one DC network with DC loads which are suitable and configured to be supplied with electrical power via a rectifier.
(2) Description of Related Art
DC networks having DC loads which are supplied with DC current via rectifiers, for example three-phase rectifiers, are known in the art, for example, from local networks of power plants. The DC loads in these local DC networks of the power plants can include DC loads related to the safe operation of the power plant. These may include, for example, sensors, field devices, display devices, display means, controllers and regulators, in particular for supplying uninterrupted power, a safety power supply, in particular a safety illumination, drives, in particular valve drives associated with a reactor vessel, and other DC loads. These electrical devices are implemented as DC devices, so that they can be easily supplied with electrical energy from an energy store, such as an accumulator or a battery. Under normal conditions, i.e., in error-free operation, these devices, such as the DC loads, are to be supplied with electrical energy generated by the power plant. The DC network with these DC loads is therefore connected by way of a rectifier to an AC voltage generated by the power plant.
However, it has been of observed in the past that these DC networks are inadequately protected against an overvoltage from the AC power grid. These overvoltages may damage the DC loads.
This may cause particularly controllers and regulators as well as sensors and actuators to fail.
Thus, there is a need to more adequately protect against an overvoltage from the AC power grid to avoid damage of the DC loads due to overvoltages.